Mumps
Introduction
- Mumps:
contagious viral illness, preventable by MMR vaccination.
- Typical
presentation: fever, headache, myalgia, anorexia → parotitis (uni- or
bilateral).
- Usually
self-limited, but complications may occur.
Epidemiology & Transmission
- Incubation:
16–18 วัน (range 12–25)
- Infectious
period: 7 วันก่อนอาการ → 8 วันหลัง parotitis onset; highest infectivity just before
parotitis.
- Transmission:
respiratory droplets, direct contact, fomites.
- Occurs
worldwide; peak late winter–early spring.
- Outbreaks:
closed environments (dormitories, schools, camps, military).
- Waning
immunity after vaccination →
outbreaks in vaccinated young adults.
- Asymptomatic
infection: 15–20%.
Clinical Manifestations
- Prodrome:
fever, malaise, headache, myalgia, anorexia (1–2 days).
- Parotitis:
hallmark, often bilateral, lasts up to 10 days; erythematous/enlarged
Stensen’s duct.
- Lab:
leukopenia + lymphocytosis, ↑serum
amylase.
- Adults:
more severe symptoms; 15–20% may be subclinical.
- Pregnancy:
no clear evidence of complications.
Complications
Genitourinary
- Orchitis
(15–30% postpubertal males)
- Occurs
5–10 days post-parotitis.
- Unilateral
60–80%, bilateral up to 10%.
- Risks:
testicular atrophy (30–50%), rare infertility/sterility if bilateral.
- Oophoritis
(5% postpubertal females) – abd pain, fever, vomiting.
- Rare:
mastitis, premature menopause.
Neurologic
- Aseptic
meningitis (1–10%): benign, full recovery.
- Encephalitis
(1:6000 pre-vaccine era): fever, AMS, seizures, paralysis. Most recover.
- Sensorineural
deafness: unilateral/bilateral, may be permanent.
- Rare:
Guillain-Barré, transverse myelitis, facial palsy.
Other
- Pancreatitis:
benign, self-limited.
- Myocarditis:
transient ECG changes common; rare severe myocarditis → dilated cardiomyopathy.
- Thyroiditis,
arthritis, nephritis: rare.
Diagnosis
- Clinical
suspicion: parotitis ± orchitis/oophoritis, relevant exposure.
- Lab
confirmation:
- RT-PCR
(buccal/oral swab, serum, CSF if neuro involvement).
- Serology:
IgM (detectable up to 4 wk), IgG (rise between acute–convalescent sera).
- Vaccinated
individuals: IgM often negative, RT-PCR less sensitive.
Specimen collection:
- Buccal/oral
swab within 3 days (not > 8 days) after parotitis.
- Acute
serum (IgM, IgG, RT-PCR). Repeat IgM if negative early.
Differential Diagnosis
- Parotitis:
other viruses (influenza, parainfluenza, EBV, CMV, HIV), suppurative
bacterial parotitis, Sjögren’s, sarcoidosis, sialolithiasis, salivary
tumor.
- Orchitis:
rubella, coxsackie, bacterial epididymitis (STI, enteric).
- Others:
lymphadenitis, drug eruption, EBV (cross-reactive IgM).
Treatment
- No
specific antiviral therapy.
- Supportive
care:
- Antipyretics,
hydration.
- Parotitis
pain: warm/cold packs.
- Orchitis:
NSAIDs, scrotal support, cold packs.
- Hospitalization
for severe orchitis, meningitis, encephalitis, or complications.
Prevention
- Isolation:
- Hospitalized:
droplet precautions until swelling resolved.
- Outpatient:
avoid contact > 5 days after onset.
- MMR
vaccine:
- 2-dose
schedule standard.
- Post-exposure
vaccine/IG: ineffective outside outbreak setting.
- Outbreak
management:
- Ensure
up-to-date immunization (2 doses).
- 3rd
MMR dose: recommended by ACIP for outbreak risk groups → reduces attack rate (esp.
if > 2 yrs since 2nd dose).
- Exclude
unvaccinated students for incubation period (12–25 days).
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✅ Key Clinical Pearls
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